package cc.ufinity.networkdiagnose.manager;
  
import java.net.*;
import java.util.*;
import java.security.*;
 

public class RandomGUID extends Object {

public String valueBeforeMD5 = "";
public String valueAfterMD5 = "";
private static Random myRand;
private static SecureRandom mySecureRand;

private static String s_id;

/**
* Static block to take care of one time secureRandom seed.
* It takes a few seconds to initialize SecureRandom.  You might
* want to consider removing this static block or replacing
* it with a "time since first loaded" seed to reduce this time.
* This block will run only once per JVM instance.
*/

static {
   mySecureRand = new SecureRandom();
   long secureInitializer = mySecureRand.nextLong();
   myRand = new Random(secureInitializer);
   try {
       s_id = InetAddress.getLocalHost().toString();
   } catch (UnknownHostException e) {
       e.printStackTrace();
   }

}


/**
* Default constructor.  With no specification of security option,
* this constructor defaults to lower security, high performance.
*/
public RandomGUID() {
   getRandomGUID(false);
}

/**
* Constructor with security option.  Setting secure true
* enables each random number generated to be cryptographically
* strong.  Secure false defaults to the standard Random function seeded
* with a single cryptographically strong random number.
*/
public RandomGUID(boolean secure) {
   getRandomGUID(secure);
}

/*
* Method to generate the random GUID
*/
private void getRandomGUID(boolean secure) {
   MessageDigest md5 = null;
   StringBuffer sbValueBeforeMD5 = new StringBuffer();

   try {
       md5 = MessageDigest.getInstance("MD5");
   } catch (NoSuchAlgorithmException e) {
       System.out.println("Error: " + e);
   }

   try {
       long time = System.currentTimeMillis();
       long rand = 0;

       if (secure) {
           rand = mySecureRand.nextLong();
       } else {
           rand = myRand.nextLong();
       }
 
       // of guessing the contents of the file!
       sbValueBeforeMD5.append(s_id);
       sbValueBeforeMD5.append(":");
       sbValueBeforeMD5.append(Long.toString(time));
       sbValueBeforeMD5.append(":");
       sbValueBeforeMD5.append(Long.toString(rand));

       valueBeforeMD5 = sbValueBeforeMD5.toString();
       md5.update(valueBeforeMD5.getBytes());

       byte[] array = md5.digest();
       StringBuffer sb = new StringBuffer();
       for (int j = 0; j < array.length; ++j) {
           int b = array[j] & 0xFF;
           if (b < 0x10) sb.append('0');
           sb.append(Integer.toHexString(b));
       }

       valueAfterMD5 = sb.toString();

   } catch (Exception e) {
       System.out.println("Error:" + e);
   }
}


/*
* Convert to the standard format for GUID
* (Useful for SQL Server UniqueIdentifiers, etc.)
* Example: C2FEEEAC-CFCD-11D1-8B05-00600806D9B6
*/
public String toString() {
   String raw = valueAfterMD5.toUpperCase();
   StringBuffer sb = new StringBuffer();
   sb.append(raw.substring(0, 8));
   sb.append("-");
   sb.append(raw.substring(8, 12));
   sb.append("-");
   sb.append(raw.substring(12, 16));
   sb.append("-");
   sb.append(raw.substring(16, 20));
   sb.append("-");
   sb.append(raw.substring(20));

   return sb.toString();
}

/*
* Demonstraton and self test of class
*/
public static void main(String args[]) {
   for (int i=0; i< 100; i++) {
   RandomGUID myGUID = new RandomGUID();
   System.out.println("Seeding String=" + myGUID.valueBeforeMD5);
   System.out.println("rawGUID=" + myGUID.valueAfterMD5);
   System.out.println("RandomGUID=" + myGUID.toString());
   }
}
} 